Polyacrylonitrile dyeing process

ABSTRACT

Fibrous material consisting of a synthetic material is dyed with a basic dyestuff in the presence of at least one member of a group of amine or nitrogen-containing compounds. Effective compounds include cyclohexylamine including alkyl substituted cyclohexylamines, furfurylamine, 1,2,3,4-tetrahydroisoquinoline, and the like. The aforesaid compounds are characterized by the ability of facilitating the migration-transfer of dye from a densely dyed or normally dyed portion of a synthetic fabric fiber to a sparsely dyed or undyed portion.

United States Patent [72] Inventor John A. Komninos Uppersaddle Rlver, NJ. [21 Appl. No. 797,978 [22] Filed Feb. 10, 1969 [45] Patented Jan. 4, 1972 [73] Assignee Clba-Gelgy Corporation Ardsley, N.Y.

[54] POLYACRYLONITRILE DYEING PROCESS 9 Claims, 2 Drawing Figs.

[52] US. Cl. 8/172, 8/177 AB [51] Int.C1. 006p 5/06, D06p 3/70 [50] Field of Search 8/84, 172, 177 AB, 85

[56] Reierenees Cited UNITED STATES PATENTS 2,125,031 7/1938 Polak et a1. 8/84 X r 2,940,813 6/1960 Taras et al. 8/85 X 2,986,444 5/1961 Rokohl et al. 8/84 FOREIGN PATENTS 1,462,130 11/1966 France 8/84 Primary Examiner-George F. Lesmes Assistant Examiner-T. .1. Herbert, Jr. Anorneysl(arl F. .lorda and Bruce M. Collins ABSTRACT: Fibrous material consisting of a synthetic material is dyed with a basic dyestufi' in the presence of at least one member of a group of amine or nitrogen-containing compounds. Effective compounds include cyclohexylamine including alkyl substituted cyclohexylamines, furfurylamine, l.2,3,4-tetrahydroisoquinoline, and the like. The aforesaid compounds are characterized by the ability of facilitating the migration-transfer of dye from a densely dyed or normally dyed portion of a synthetic fabric fiber to a sparsely dyed or undyed portion.

POLYACRYLONITRILE DYEING PROCESS FIELD OF THE INVENTION The present invention relates to a new and improved method for dyeing fibrous material and particularly, fibrous material consisting of a synthetic material such as a polyacrylonitrile by a procedure involving contacting said fibrous material, in an aqueous dyebath, with at least one member of a group of amine or nitrogen-containing compounds which acts as a migrating agent. It has been found that by the use of the migrating agents of the present invention, there is obtained a more uniform redistribution of the dye on the synthetic fibers and fabrics than has been hitherto possible.

DESCRIPTION OF THE PRIOR ART Fibers of polyacrylonitrile and acrylonitrile copolymers are being increasingly dyed with basic dyestuffs having a high affinity for the fiber; the dyestuffs consequently go on almost completely and very fast dyeings are obtained. However, because of the rapid absorption of the dyestuff due to its high affinity, this leads to uneven dyeings when the dyeing is effected in the temperature ranged of 185F. to boiling temperature and especially, in the temperature range of 194 to 205 F. This problem can only be remedied, in some cases, by careful temperature regulation that is, by slowly increasing the temperature during the dyeing.

In an attempt to increase the absorption and improve the evenness of the dyeings, certain substances generally referred to as dyeing assistants are added to the dye bath to promote or to control dyeing. Such substances aid in the achievement of uniform absorption of the dye by the fiber. The manner in which the level-dyeing is accomplished depends, generally, upon the particular dyestuff in use and also upon the substance which is employed as a dyeing assistant. Usually, a dyeing assistant will aid in promoting level deposition of the dye on the fiber or fabric in several ways. For example, certain dyeing assistants will promote leveldyeing by increasing the solubility of the dye in the bath. Other dyeing assistants however, will accomplish the desired result by delaying the absorption of the dye by the fiber. Still other dyeing assistants will function as such by aiding the dye to penetrate more readily the material to be colored. However, in many cases, it has been found that the addition compounds formed between the dyestuff and the aforesaid dyeing assistants are very stable and in the course of the dyeing process, the dyestuff is only partially liberated even if the temperature is increased. As a result, considerable amounts of dyestufi's are lost during the dyeing process and, because of the loss of considerable amounts of dyestuff during the dyeings, only pale shades of the dyed material are obtained.

In an attempt to avoid the aforesaid difficulties with respect to dyeing, retarders have been employed to cause the rate of strike to become slower at the critical temperature that is, at the temperature between l80and 200 F. Two types of retarders have been generally used; the first type is the cationic retarder and a substance of this type functions by competing with the dye for the available dye sites. A cationic retarder has more affinity for the dye site and, due to its smaller molecular size, is able to precede the dye at slightly lower temperatures. As a result, less dye sites are available at temperatures between about 180 and 200 F. and the shortage of sites causes the dye to seek out vacant sites and draw out of the bath evenly. It has been shown that with this retarder system, the dye strike from 200 206 F. is extremely rapid and this further narrows an already dangerously narrow temperature range.

Since cationic retarders are nearly permanent in their occupancy of dye sites, they present a barrier to the movement of dye from a more heavily dyed area. Migration is, therefore inhibited by the use of cationic retarders. Another disadvantage associated with the use of cationic retarders is that they further separate differential dyeing characteristics of cationics making the slow color dye slower relative to faster exhausting colors. Still another disadvantage is that the presence of the strong retarder reduces the dye buildup and makes redyeing to darker repair shades difficult if not impossible. Then, it has been found that cationic retarders are dependent on dyestuff concentration and the less dye used the more retarder will be necessary. Another criticism of the use of cationic retarders is that they block out cationic softener aftertreatments. In addition, cationic retarders usually work against or prevent migration because retained retarder blocks out transferring dye.

A second type of retarding agent used is an anionic retarder and such a system functions through the formation of a complex or anionic surfactant with the cationic dye. In order to prevent precipitation, the complex is stabilized by being held in a dispersed form in the bath by a nonionic surfactant. The larger size particle of the complex attaches itself to the fiber surface at temperatures even lower than that containing no retarder. In this manner, the otherwise very narrow strike temperature range is widened. At sustained temperatures above 190 F., the complex dissociates slowly thus giving up the dye to the dye site uniformly. Unfortunately, the disassociation is not complete as a portion of the dispersed complexed dye "1 remains associated throughout the entire dye cycle resulting in lower yields than those obtained by the use of cationic systems. Further, anionic retarders allow only slightly better migration than cationic retarders and the major appeal of the former is in special areas where bulking shrinkage is otherwise inhibited or where cationic-anionic dye combinations are required for blends.

Another problem which must be contended with in dyeing procedures is migration and especially so when contending with the dyeing of acrylics. The temperatures required to migrate wool dyes are much lower than those needed for cationic dyes on acrylic fibers. It has been found that the ternperature needed is high, that is, above the boil and consequently, pressurized equipment is necessary. The use of such equipment represents a problem which dyers wish to avoid not only from the point of view simplifying the process but also from the point of view of minimizing the cost. In addition, fabrics and particularly, acrylics, do not lend themselves to pressuredyeing.

Thus, in the dyeing procedure, the dyer is faced with the problem of a balance between retardation and migration since it is almost impossible to obtain both efiects. The problem is further complicated by the fact that retarder systems, when used at high concentrations, can nullify the beneficial effect of migration aids. For example, the retained or residual cationic retarder can block out the transferring dye. This effect is more evident at lower temperatures that is, at temperatures of about 180 F. while at higher temperatures, i.e., temperatures of about 212F., the cationic retarder causes somewhat less interference with migration. However, at no time within the temperature range of l"2l2 F., are all of the dyesites available. Thus, the attempts at black shade redyeing of bad lots, previously dyed in the presence of strong cationic retarders, have shown the permanence of at least some of the dye siteretarder linkage.

In the case of the use of anionic retarders, a similar problem exists although this problem is not quite as severe. The complex of dye and anionic surfactant once broken, leaves the excess anionactive material in the bath and this material is free to complex with the dyestuff moving from the fiber into the bath and prevent, at least partially, a further exhaustion onto another dye site. Since the anionic retarder does not occupy dye sites, those anionic retarders of low dye concentration are more apt to receive transferred dye than in a cationic retarder system.

SUMMARY OF THE INVENTION In accordance with the process of the present invention, fibrous material consisting of a synthetic material such as, for example, a polyacrylonitrile, is dyed by contacting the aforesaid fibrous material as, for example, by immersion in an aqueous bath containing a basic dyestuff and at least one migrating agent selected from a group of amine or nitrogencontaining compounds. The aforesaid migrating agents have been found to maintain the effective dyeing temperature range and surprisingly, by the present procedure, it is possible to avoid resorting to temperatures above the boil in order to transfer the dye. Thus, the migrating agents of the present invention have been found to be helpful in softening the fiber at temperatures below the glass transition temperature of the polymeric material and that in addition, once having removed the dye from its original fixed position, he present migrating agents allow the return of the dye to a new position. In addition, it has been found that by using the present process, it is possible to avoid the use of or drastically reduce the amount of a retarder used and in place thereof utilize a migrating agent which can produce a redistribution of the dye to a more uniform appearance on synthetic fibers and fabric and especially acrylic fibers and fabrics, than has been heretofore possible.

Further, by use of either a cationic or anionic retarder, significant transfermigration of dye, under 212 F., is possible, once a linkage of dye with the fiber dye-site is made. In a cationic dyeretarding system, the retarding agent and other analogous cationic auxiliaries serve to strip off a modicum of linked dye but do not allow it to transfer back on to a new dye site that is, the aforesaid substances behave, in reality as antimigration agents. ln'the anionic retarder system, in most instances, the migratingtransfer agents are chemically incompatible and/or ineffective. Surprisingly, it has now been found that the active agents of the present process accomplish a significant transfermigration in both the cationic and anionic retard systems.

Still further, by using the present process, it is now possible to check the migrationtransfer of a dye from a densely dyed or normally dyed portion of a synthetic fiber and particularly an acrylic fabricfiber to a sparsely dyed or undyed portion.

Thus, a level and more uniformappearing dyed textile structure is produced in open equipment (up to sea level atmospheric boil) that would otherwise require closed equipment (autoclaves capable of temperatures in excess of atmospheric boil).

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a new and improved procedure for dyeing fibrous material and particularly, fibrous material consisting of a synthetic material such as, a polyacrylonitrile, by a process involving contacting the said fibrous material, as, for example, in an aqueous dyebath containing a basic dyestufi, with an amine or a nitrogencontaining compound which acts as a migrating agent. The migrating agent is used in amounts up to about 10 percent, by weight, relative to the weight of the fibrous material.

The fibrous material which is dyed by the use of the process of the present invention, includes, for example, syntheticfibrous materials consisting essentially of at least 50 percent of polyacrylonitrile such as, for example, copolymers of acrylonitrile with vinyl compounds such as vinyl alcohol, vinyl acetate, vinyl propionate, vinyl chloride, vinyl bromide, vinylidene chloride, vinyl pyridine, vinyl imidazole, acrylic acid esters, methacrylic acid esters, alphacloracrylic acid esters, acrylic and methacrylic acid amides, nd the like, containing a considerable and advantageously, a predominant portion of polyacrylonitrile. The fibrous material may also consist of a mixture of polymers containing one or more of said monomers with polyacrylonitrile, the latter material again preferably predominating. Illustrative polyacrylonitrile fibrous materials include, Orlon (particularly Orlon Type- 42 Fiber), Acrilan (consisting of 85 percent acrylonitrile and 15 percent vinylacetate), and the like.

The active amine compounds or nitrogen-containing compounds which can be used in the present process involving a new and improved procedure for dyeing fibrous materials are:

cyclohexylamine including alkyl-substituted cyclohexylamines furfurylamine including alkylsubstituted furfurylamines benzylamine including alkyl substituted benzylamines 1,2,35,4-tetrahydroisoquinoline l,2,3,4- tetrahydroquinoline imidazole 2- methyl imidazole 2- methylbenzimidazole N- benzyl- 4- picolinium chloride alpha picoline tetrahydrofurfurylamine N- benzyl quinolinium chloride tributylamine and secondary butylamine 2- ethylhexyl- 3- amino propyl ether methylpiperidine including other alkylsubstituted piperidines such as ethyl-propyl-, butyl piperidines, and the like N,N- dibenzylamine tribenzylamine nseetertbutylamine and salts of the aforesaid amines as well as mixtures of l) cyclohexylamine, benzylamine, imidazole and furfurylamine and (2) cyclohexylamine, benzylarnine,

imidazole and 2- ethylhexyl- 3- amino propylether. Including among the alkylsubstituted cyclohexylamines are methyl cyclohexylamine, ethyl cyclohexylamine, isopropyl cyclohexylamine, and the like; illustrative of the alkylsubstituted benzylamines and furfurylamines are N-benzylmethylamine, N- furfurylamine, and the like.

It has been found that salts of the amines or the nitrogencontaining compounds can also be advantageously used in the present process and these salts are derived from halogen hydracids such as, hydrochloric acid, hydrobromic acid, and the like; from mineral acids of medium to high strength such as, for example, sulfuric acid, phosphoric acid, and the like; from organic acids of medium to high strength as well as other acids such as lower alkyl sulfuric acid monoesters, formic acid, acetic acid, oxalic acid, tartaric acid, succinic acid, sulfosuccinic acid, thiocyanic acid, and the like.

Illustrative of the basic dyes which can be used are fuchsin, methyl violet, aniline blue, dyestuffs of the diand triarylmethane series, the azine, oxazine and thiazin series, Xanthene dyestuffs, acridine dyestuffs, quinoline dyestuffs, quinophthalone dyestuffs, cyanine and methine dyestuffs, basic azoand basic anthraquinone dyestuffs, the indolyland diindolylarylmethane series, diazine, induline, and the like.

The active compounds used in the present process are known. These compounds are soluble in water; they are not surfaceactive and do not foam; additionally they do not impair the fastness of the dyeings.

The levelling agents may be used during the dyeing procedure; about 0.25 to 5 percent is required with reference to the weight of the fiber or other structure of synthetic material. The levelling agents may also be used for levelling up after dyeing; in general, larger amounts are required for this purpose-about 1.5 to 10 percent with reference to the weight of the fiber or other structure, in the blank dyebath. The period for the dyeing may vary between about 0.5 and 8 hours; preferably, the duration of the procedure is between about I and 3 hours. Similar periods may be used for the levelling. The addition of the active compound may be made prior to the dyeing process or at the beginning and/or in the course of such process. It is also possible to pretreat the fibrous material with the active compounds of the present invention.

The active migrating agents of the present invention have excellent activity in all dyeings of basic dyestuffs on textile materials in the form of films, foils, thread, fibers, flocks, fabrics and similar structures of every kind such as, for example, yarn, or knitted or woven fabric which have been made from polyamides, polyesters, or polymers or copolymers containing acrylonitrile. The fibrous material may be a polyacrylonitrile or an acrylonitrile copolymer. The term acrylonitrile polymers is intended to include homopolymers of acrylonitrile and also copolymers which can contain about 50 EXAMPLES 1-15 In the examples, the indicated test dyes were applied at a 2 percent depth in a bath containing percent Glaubers salt and the pH was adjusted to 4.5 with acetic acid (56 percent). After dyeing for 1 to 2 hours at temperatures between l80"-212 F., the swatches were placed in a fresh bath containing the various migrating agents, at the indicated o.w.f. (on weight of fabric), 10 percent Glaubers salt and the pH was adjusted to 4.5 with acetic acid (56 percent). Comparisons were made with the known migrating agents benzyl trimethyl ammonium chloride as well as the alkyl (C -C benzyl dimethyl ammonium chloride.

important factor for levelness, reproducibility and computerized colorimetric control.

A horizontal line at the 100 percent level of the vertical axis indicates zero desorption as does a horizontal line at the 0 percent level indicate zero absorption. When A (percent absorbed) equals D (percent desorbed), colortransfer efficiency is at a maximum. However, colortransfer ratio (CTR) is the more important factor in that it quantifies the amount of D in relation to the amount of A. When this /50, the sum of numerator and denominator of CTR is at a maximum and equals I00.

In freshbath migration of conventional acrylic dyeing systems involving the use of known quaternary rctarders and migrating agents, colortransfer is usually asymmetric and of a very low quantitative order. The results set out in table 1 supra bear this out. It was surprising to find that the migrating agents .of the present invention produce symmetrical and uniform migration of a much higher quantitative order as compared with the known quaternary agents. The difference in form (symmetry) and quantity (percent color transferred) produced by these active nitrogen containing and amine compounds of the present invention is directly related to the acceptance or rejection of a dyeing as to uniform or level appearance and its reproducibility via visual or computerized colorimetric means.

FIG. 1 illustrates a 2 percent (o.w.f.-on weight of fabric) TABLE I.MIGltATION TABLE (D -C BOI'IZYI benzyl tril-ethyl dimethyl methyl lrexyl 3 amrnoammo- Cyelo- Furamino nium nium llcxyl Benzyl furyl propyl Imid- Percent Percent Dyeing, percent chloride chloride amine amine amine ether azol desorbed absorbed Form Sum of dyestuffs on color Ex. Orlon 42 (Percent on weight of fabric) transfer 1 0 0 0 2 2 Asymmetric 6 3 25 25 Symmetrical. 50 4 1.0% Basic Red 22," 44 5 56 6 5; 7 54 8 {22% Basic Red 22 l. .70" Basic Blue 41 72 0 1.30% Basic Yell. 10 10 {15% Basic Rctl 18".. 10 4 Asymmetri l4 .75% Basic Yell. l9 28 28 Symmetrical 56 -}1.0% Basic Blue 3..

On migration graphs set out in FIGS. 1 and 2, the uppermost point on the percent dyed vertical axis of the 100 percent signifies a fully dyed fabric. An undyed fabric of equal previous dyecycle experience without color is indicated at 0 percent. The horizontal axis indicates time in minutes. By introducing a dyed and undyed piece of acrylic fabric into a hot liquor, the desorption from the dyed piece is plotted with the absorption of the undyed piece against time. The nearer and sooner these two curves approach each other the more effective is the migrating agent.

A normal fresh bath migration test commences with equal weights of 100 percent and 0 percent dyed fabric (Orlon- 42 knit) at a given temperature in a bath containing acetic acid to adjust the pH to 4.5, 10 percent Glauber's salt, and the indicated amount of the chemical migrating agents under investigation.

When the dye that desorbs from the dyed fabric is completely absorbed by the undyed fabric, the color transfer is observed to be symmetrical. When there is greater desorption than absorption, color-transfer is observed to be asymmetrical. In asymmetrical migration, the excess dye remains in the dye-bath liquor and is, for all practical purposes, lost. Asymmetry also indicates that the migration of component dyes cannot be isotonal or onshade in relation to input ratio of components. Isotonality during dyeing and migration is an dyeing of Basic Red 22 with 10 percent Glauber's salt, acetic acid (56 percent) adjusted to a pH 4.5. Dyeings were conducted at a liquor ratio of 20:1. The two migration curves that approach each other closest and soonest were dyed and migrated with the 1.0 percent (o.w.f.) of a composition containing the indicated amine and nitrogen-containing compounds. The curves are symmetrical. The two curves that show very little desorption and less absorption (asymmetry) were dyed and migrated with the conventional alkyl benzyl dimethyl ammonium chloride. Similar migration behavior of selfshades and combination shades exists with conventional cationic dyes.

FIG. 2 illustrates the use of Dark Brown, a combination of 3 cationic dyes, i.c., 0.22 percent Basic Red 22, 0.70 percent Basic Blue 4i and 1.30 percent Basic Yellow l9, on Orlon- 42 knit. Similar amounts of Glauber's salt, acetic acid and the same pH were used here as in FIG. I. The asymmetry shown by the control migration is evidenced visually as a dull pink whereas the symmetrical migration results in an ontone brown.

Further, it has'been found that the quaternary chemicals used in conventional dyeing, such as, for example, fatty alkyl benzyl dimethyl ammonium halides or in lesser alkyl moiety size as far down as benzyl trimethyl ammonium chloride, are ionexchanged with the acrylic dye site and are thereby dyestuff in a progressively additive way up to saturation. How

ever, with the conventional system, the quaternaries used contribute to saturation and also block out dyes that may be added to change the original shade to darker or different hues. In addition, by using the migrating agents of the present invention, it is possible to lessen or lighten shades evenly, i.e., in repairing of goods.

This invention has been disclosed with respect to certain preferred embodiments and various modifications. Variations thereof will become obvious to persons skilled in the art. it is to be understood that such modifications and variations are to be included within the spirit and scope of this invention.

We claim:

1. A method of dyeing fibrous material consisting essentially of a polyacrylonitrile, which comprises contacting said fibrous material, in an aqueous bath containing a basic dyestuff and at least one nitrogencontaining compound selected from the group consisting of cy clohexylamine, alkylsubstitutec cyclohexylamine, furfurylamine, alkylsubstituted fur furylamine, acid salts of said cyclohexylamines and furfurylamines, l,2,3,4- tetrahydroisoquinoline, a mixture of cyclohexylamine, benzylamine, imidazole and furfurylamine and a mixture of cyclohexylamine, benzylamine, imidazole and 2- ethylhexyl- 3- amino propylether.

2. A process according to claim 1 wherein the fibrous material consists predominantly or entirely of polyacrylonitrile.

3. A process according to claim 1 wherein the fibrous material consists of a polyacrylonitrile copolymer.

4. A process according to claim 1 wherein the amine or ---,nitrogencontaining compound is present in an amount ranging between 0.25 and 10 percent by weight, relative to the weight of the fibrous material to be dyed.

5. A process according to claim 1 wherein the amine compound is cyclohexylamine, an alkylsubstituted cyclohexylamines or an acid salt thereof.

6. A process according to claim 1 wherein the amine is furfurylamine or an acid salt thereof.

7. A process according to claim 1 wherein the nitrogencontaining compound is l,2,3,4- tetrahydroisoquinoline.

8. A process according to claim 1 wherein the amine or nitrogencontaining compounds are a mixture of cyclohexylamine, benzylamine, furfurylamine and imidazole.

9. A process according to claim 1 wherein the amine or nitrogen-containing compounds are a mixture of cyclohexylamine, benzylamine, imidazole and 2-ethylhexyl 3-amino propylether. 

2. A process according to claim 1 wherein the fibrous material consists predominantly or entirely of polyacrylonitrile.
 3. A process according to claim 1 wherein the fibrous material consists of a polyacrylonitrile copolymer.
 4. A process according to claim 1 wherein the amine or nitrogen-containing compound is present in an amount ranging between 0.25 and 10 percent by weight, relative to the weight of the fibrous material to be dyed.
 5. A process according to claim 1 wherein the amine compound is cyclohexylamine, an alkyl-substituted cyclohexylamines or an acid salt thereof.
 6. A process according to claim 1 wherein the amine is furfurylamine or an acid salt thereof.
 7. A process according to claim 1 wherein the nitrogen-containing compound is 1,2,3,4-tetrahydroisoquinoline.
 8. A process according to claim 1 wherein the amine or nitrogen-containing compounds are a mixture of cyclohexylamine, benzylamine, furfurylamine and imidazole.
 9. A process according to claim 1 wherein the amine or nitrogen-containing compounds are a mixture of cyclohexylamine, benzylamine, imidazole and 2-ethylhexyl 3-amino propylether. 